tried out a couple that a friend has. liked the curved one the best, but so did he, and the straight one he gave me never saw much use. never seen a curved one at a yardsale, but I finally purchased a curved one from the hardware store. Came from the same pile that JW's did, and was waaay to soft to hold an edge. finally got pissed at it staring at me with a new $50 price tag, so I grabbed the torch and hardened it, retempered to straw color, and it now sharpens up fine and I can roll the edge with the same effort as a cabinet scraper. with all the work I got in it, I should have just found an old leaf spring and saved me the $50. If you can build a bow, than a drawknife is an ez metal project.
Picked up the straight one to try again yesterday while reducing a stave, and put it right back down again. Gotta be curved -for me anyway. May be there's a reason you see so many straight ones at the antique stores, although I cant believe that the drawknife gets much attention in the typical tool box in todays age of power tools. I have been sawing, planing and grinding wood with electricity for 40 years in trade related ways, and appreciate the lack of dust and noise that comes with hand tools.